Abstract:Species of the genus Pseudoplatystoma, the long-whiskered catfishes, are important in commercial and recreational fisheries in South America, and some species have become key to regional aquaculture. Some species of the genus are under pressure due to overfishing and the negative impacts of dams. Six questions are asked in this review: (i) What species are in the genus, and where are they distributed? (ii) What are the life histories and ecologies of Pseudoplatystoma species? (iii) What are the patterns of som… Show more
“…Our findings showed that females exhibit a higher sex ratio, length, and weight compared to P. punctifer males. The dominance or size structure of individuals in one sex over the other may be related to differential individual growth rates and early gonad maturation (Pereira et al, 2023;Suzuki et al, 2013). However, females invest significantly more effort in reproductive development compared to males (Barneche et al, 2018;Freitas & Montag, 2019).…”
Section: Discussionmentioning
confidence: 99%
“…Hydroelectric dams can cause deleterious consequences for fish populations, including the surubim, as they prevent reproductive migrations, and reduce individual biomass and spawning potential, reflecting negatively on the recruitment of natural stocks and fisheries productivity (Andrade et al, 2019;Pereira et al, 2023).…”
Fish is an important source of food and income for a significant portion of the Amazonian population, especially those who live along the rivers and lakes in the region. Pseudoplatystoma punctifer (Castelnau, 1855), known as surubim, is a species of Neotropical catfish widely exploited by fisheries and commercially valuable in the Guaporé River basin, Brazil. However, population dynamics are poorly known in the region. To understand the population structure and reproductive biology aspects of the surubim, monthly experimental fisheries were carried out in the São Miguel River, state of Rondônia, Brazil, between August 2020 and July 2021. The captured fish were weighed, and its gonads were removed and weighed for histological analyses (microscopic description) and classification of the maturation stages (macroscopic description). The collected gonads were fixed in 10% buffered formalin, dehydrated, cut into 4‐μm‐thick sections, and stained with hematoxylin and eosin. A total of 34 individuals were collected (20 females and 14 males), showing positive allometric growth and condition factor from 0.81 to 1.79 for females and males, respectively. Females were larger in size and weight than males. P. punctifer reaches its first maturation at an average length of 68.30 cm, indicating the importance of respecting the minimum capture size as an alternative to ensure the natural stocks of this fishery resource in the region. The results provide support for the establishment of public policies and actions for conservation, management, and regulation of fishing.
“…Our findings showed that females exhibit a higher sex ratio, length, and weight compared to P. punctifer males. The dominance or size structure of individuals in one sex over the other may be related to differential individual growth rates and early gonad maturation (Pereira et al, 2023;Suzuki et al, 2013). However, females invest significantly more effort in reproductive development compared to males (Barneche et al, 2018;Freitas & Montag, 2019).…”
Section: Discussionmentioning
confidence: 99%
“…Hydroelectric dams can cause deleterious consequences for fish populations, including the surubim, as they prevent reproductive migrations, and reduce individual biomass and spawning potential, reflecting negatively on the recruitment of natural stocks and fisheries productivity (Andrade et al, 2019;Pereira et al, 2023).…”
Fish is an important source of food and income for a significant portion of the Amazonian population, especially those who live along the rivers and lakes in the region. Pseudoplatystoma punctifer (Castelnau, 1855), known as surubim, is a species of Neotropical catfish widely exploited by fisheries and commercially valuable in the Guaporé River basin, Brazil. However, population dynamics are poorly known in the region. To understand the population structure and reproductive biology aspects of the surubim, monthly experimental fisheries were carried out in the São Miguel River, state of Rondônia, Brazil, between August 2020 and July 2021. The captured fish were weighed, and its gonads were removed and weighed for histological analyses (microscopic description) and classification of the maturation stages (macroscopic description). The collected gonads were fixed in 10% buffered formalin, dehydrated, cut into 4‐μm‐thick sections, and stained with hematoxylin and eosin. A total of 34 individuals were collected (20 females and 14 males), showing positive allometric growth and condition factor from 0.81 to 1.79 for females and males, respectively. Females were larger in size and weight than males. P. punctifer reaches its first maturation at an average length of 68.30 cm, indicating the importance of respecting the minimum capture size as an alternative to ensure the natural stocks of this fishery resource in the region. The results provide support for the establishment of public policies and actions for conservation, management, and regulation of fishing.
“…One species for which no studies have investigated the effects of interannual variability in flood pulses on growth is Pseudoplatystoma fasciatum. This catfish species transports nutrients and connects habitats through migration [31,32]. It is also a source of food security and income for riverine people in the Amazon basin.…”
Section: Introductionmentioning
confidence: 99%
“…This species is heavily fished and may be threatened by the growing construction of hydropower dams [33]. P. fasciatum is distributed in four countries of the Amazon basin, including the Amazon mainstem and the Madeira, Solimões, and Tapajós tributary rivers [31]. Understanding how interannual variability in flood pulses affects its growth is key to managing and conserving it.…”
Section: Introductionmentioning
confidence: 99%
“…The eggs and larvae of P. fasciatum drift downstream with the current during the high-water season (typically referred to as the peak-flow period) when adults and juveniles migrate laterally to the floodplains to prey on other fish and grow faster. During the falling-water season (typically referred to as the descending limb), P. fasciatum migrates back to the mainstream river and stays there for the low-water season, where it predates less and grows more slowly [31]. In line with this migratory ecology, growth studies showed that the vertebrae of P. fasciatum deposit one growth ring per year [32,34], with slower growth (opaque ring formation) occurring during the low-water season and faster growth (the hyaline ring) in the rising-water season.…”
Fish growth is a fundamental biological process driven by a multitude of intrinsic (within-individual) and extrinsic (environmental) factors that underpin individual fitness and population dynamics. Interannual variability in river hydrology regarding the intensity and duration of floods and droughts can induce interannual variations in the biotic and abiotic variables that regulate fish growth. However, the understanding of how interannual variability in river hydrology affects fish growth remains limited for most species and ecosystems. We evaluated how inter-annual hydrological variations within the Amazon River basin influence the growth of the catfish Pseudoplaystoma fasciatum. Our research questions were as follows: Do floods lead to the faster growth of P. fasciatum and droughts lead to the slower growth? And do floods and droughts affect all age classes in the same manner? We sampled 364 specimens of P. fasciatum from five sites in the Amazon basin, estimated their growth rates, and related the growth rates to indices of the intensity of floods and droughts. We fitted linear mixed-effects models to test the relationship between growth increments and hydrological indices (with F and D quantifying the intensities of floods and droughts, respectively), age as fixed effects, and basins and Fish ID as random effects. We found an inverse relationship between the increment width in the fish hard parts and hydrological indices. That is, intense floods and droughts negatively affected the growth rates. We also found that the growth of P. fasciatum was no different in years with intense and mild floods across age classes 1–5, although was different for age class 6. However, the growth of P. fasciatum was faster in years of mild droughts for all age classes. Our results showing that the growth of P. fasciatum was slower in years of intense droughts are supported by those of previous studies in the Amazon basin and elsewhere. However, our results showing for the first time that the growth of P. fasciatum is slower in years of intense flooding is the opposite of patterns found in other studies. These results thus suggest that the growth of P. fasciatum is maximized within an optimum range of hydrological conditions, where neither floods nor droughts are intense.
Fish migrate for varied reasons, including to avoid predators and to access feeding, spawning, and nursery habitats, behaviors that enhance their survival and reproductive rates. However, the migratory ecology of many important fishes, especially those in river–floodplain ecosystems, remains poorly understood. One fish of the Amazon Basin whose migratory behavior is poorly understood is the catfish Pseudoplatystoma fasciatum. Here, we used otolith elemental microchemistry to characterize the migration ecology of P. fasciatum in the Amazon Basin. The main research questions of this study were: (1) does P. fasciatum move between waters with different Sr isotopic signatures (87Sr/86Sr) and chemical compositions? (2) What distance do they migrate? (3) Is the migration of P. fasciatum related to age? And (4) does P. fasciatum migrate mainly upstream, downstream, or in both directions? We assessed whether P. fasciatum migrates between waters with different 87Sr/86Sr values, comparing the Sr isotopic signature of otolith transects of each individual with the range of Sr isotopic signatures within the respective rivers. We found that 34% of the 71 fish analyzed migrated between rivers with different Sr isotopic signatures and 66% did not. The mean migration distance migrated was 126 km, with most specimens migrating between 72 and 237 km. Apparently, no fish of age one or age six or older migrated. All fish that migrated were between two and five years of age, with 20% of the specimens that migrated being two years old, 40% three years old, 30% four years old, and 20% five years old. Sixty-six percent of all individuals that migrated between rivers with different Sr signatures did so bidirectionally, while 33% moved unidirectionally. According to our definition of homing behavior in which fish migrated back to the same river where they were born, 41% of all fish that migrated displayed apparent homing behavior. Our findings provide insights into the migratory ecology of P. fasciatum, corroborating and refining knowledge reported in the literature. Our results on the migratory ecology of P. fasciatum have implications for sustainable fisheries conservation and management: conserving P. fasciatum requires habitat maintenance and suitable fishing practices in spawning and nursery habitats, and managers must consider large geographic areas for effective fishery management and conservation.
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